Beat-to-Beat Variability in Stroke Volume During VVI Pacing as Predictor of Hemodynamic Benefit from DDD Pacing. - Dritsas, Athanase; Joshi, Jayshree; Webb, Stuart C.; Athanassopoulos, George; Oakley, Celia M.; Nihoyannopoulos, Petros (Pacing & Clinical Electrophysiology, 1993)